I like playing around with photos. As you know I’ve converted some images to silhouettes for my vinyl wall art, but here is how I change my digital photos to line art (using Photoshop CS4) so I can color them later and add to my projects. You can take a picture of anything you like and do this for greeting cards. The ideas are endless. This guy’s video is very helpful.
Here's an image I converted (my daughter's first time twisting her own hair :-) ). I didn't do any editing, but when I get ready to use the photo, I will make some changes based on the project.
Here's a photo of my daughter when she was 6 or 7. I thought I would try a photo with a busier background just to see how it would look. I can see some really dark edges on her hair, but not sure how to fix that or why it happened. I tried changing the radius from 2 to 3, but the photo was not looking too good, so I stayed with a radius of 2. I am sure there is a way to fix it, but I am not a Photoshop pro by any means. :-)
Here's one of my favorite photos of Jaden Smith converted to lineart with Photoshop CS4. I really like the way the background of photos are so clear.